In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, one way to improve the overall network performance may be to complement so-called macro cells with so-call small cells, such as micro cells or pico cells, to provide higher capacity and bit rates. To make efficient small cell deployments a high level of integration and coordination in the mixed macro- and small cell network is required.
In addition, frequency spectrum is constantly deployed into new and existing communications networks and the communications networks may therefore be configured to handle a growing amount of frequency layers. This leads to increased challenges for the radio access network part of the communications network and for the wireless devices served by the communications network in terms of finding other frequency layers, especially in environments with a mix of macro cells and small cells. To identify neighbor cells in Long Term Evolution (LTE) communications networks the wireless device (referred to as user equipment, UE) has to perform inter-frequency measurements as disclosed in 3GPP TS36.331 Release 8 or later. So called measurement gaps are commonly required to enable wireless devices to perform these measurements. These measurement gaps will occupy resources from data traffic. Hence the communications network may be configured to request the inter-frequency measurements as rarely as possible to not degrade the performance of the communications network. These measurement gaps are commonly 6 ms long and be repeated every 40 ms or 80 ms. During these measurement gaps, and up to 4 ms before the measurement gaps it is not possible to schedule the wireless devices in order to avoid Acknowledge/Not Acknowledge (ACK/NACK) signals to be missed. This results in a loss of up to 25% of throughput in the downlink (i.e., transmission from radio access network node to wireless device). Further, intra-frequency measurement gaps may collide with system information and/or Multimedia Broadcast Multicast Services (MBMS) broadcast. This will increase the time for a wireless device to receive, as well as send, system information and/or MBMS data. In case the measurement gaps and the broadcast information collide the information will be lost completely. Inter-frequency measurements are examples of mobility measurements
Advanced traffic management may thus be required in the communications network to secure that the wireless device always is operatively connected to the best serving cell and corresponding frequency band. The decision of what cell is the best cell and what frequency band is the best frequency band may be based on parameters such as wireless device speed, subscriber profile and/or, load and service-awareness.
So-called Self-Organized Network (SON) mechanisms (inter alia disclosed in 3GPP TS36.902 Release 8 or later) have been developed to provide automatic configuration and optimization of the radio access network. Existing SON mechanisms may be used for self-configurations, for network optimization and for self-healing purposes.
When SON is used for self-configuration, interfaces (such as interfaces S1 and X2) in the radio access network are dynamically configured, as well as the Internet Protocol (IP) address and connection to the IP backhaul. In addition, Automatic Neighbor Relations (ANR) may be used to further automate the radio access network configuration. For example, with ANR the neighbor cell lists in newly deployed radio access network nodes are automatically configured and optimized during operation.
An additional functionality that aims to optimize network deployments in an automated way is denoted Mobility Robustness Optimization (MRO). MRO is capable of automatically detecting and correcting mobility errors causing radio link failures. MRO is capable of detecting radio link failures caused by handover of a wireless device being performed to an incorrect cell, or being performed too late or too early handover, and automatically adjusting the related mobility settings.
Hence, there is still a need for an improved handling of mobility measurements.